The cell envelope antigens of Propionibacterium acnes and related bacteria are to be analyzed chemically and immunologically with the objective of relating antigenic types with biologic activity, especially infectivity and adjuvanticity. Emphasis is to be placed upon analysis of the teichoic acids and lipoteichoic acids using techniques developed by Baddiley, Ghuysen, Knox and others. Degradation of immunodominant groups is to be avoided by reliance upon enzymatic cleavage of the murein polymer of cell wall followed by chromatographic isolation of the teichoic acid-peptidoglycan complex. Lipoteichoic acids will be extracted from lysozyme-derived protoplasts with cold phenol. Antigenic analysis will rely on inhibition of quantitative precipitation and passive hemagglutination.